Electromagnetic coil construction

ABSTRACT

AN ELECTROMAGNETIC COIL CONSTRUCTION IS DESIRED IN WHICH THE COMPONENT ELEMENTS COMPRISE A BOBBIN OF THERMOPLASTIC MATERIAL AROUND WHICH THE WIRE IS WOUND. THE BASE FLANGE OF THE BOBBIN HAS A HOLLOW PORTION, THE WALL OF WHICH SUPPORTS TERMINAL INSERTS. A THERMOPLASTIC COVER OVER THIS PORTION LOCKS THE INSERTS IN PLACE. A TUBULAR SHELL PLACED OVER THE BOBBIN ENVELOPS THE WINDING. THE RIM OF THE SHELL, AS WELL AS THE RIM OF THE FLANGE, ARE TAPERED AT THE EDGE OF SONIC WELDING OF THE SHELL AND THE COVER TO THE BASE FLANGE.

Feb. 2, 1971 5, FOLDES ET AL" 3,560,903 i f Q ELECTROMAGNETIC coI'L CONSTRUCTION. v Filed Jan. 30*, 1969 2 Sheets-Sheet 1 lNVENTORS STEPHEN FOLDES LOUIS A. JIMENEZ BY ffiUMC M M Q) ATTORNEY Feb. 2, 1971 s, FQLDES ET AL ELECTROMAGNETIC COIL CONSTRUCTION Filed Jan. 30, 1969 INVENTURS STEPHEN FOLDES LOUIS A. JIMENEZ ATTORNEY United States Patent 3,560,903 ELECTROMAGNETIC COIL CONSTRUCTION Stephen Foldes, 38 Front St. 13905, and Louis A.

Jimenez, 524 Midvale Road 13903, both of Binghamton, N.Y.

Filed Jan. 30, 1969, Ser. No. 795,151 Int. Cl. H01f 15/10, 27/30 US. Cl. 336-92 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an electromagnetic coil construction, particularly of the type used in relays, solenoids and similar applications. Coils for producing an electromagnetic flux for the actuation of relays and solenoids have been in use in various forms and consist essentially of a bobbin around which a required number of turns of an insulated wire is wound and a support for mounting the assembly to perform its intended function. In most applications the coil resulting from the winding of the Wire represents a delicate assembly inasmuch as the wire size, in order to obtain a large number of turns in a relatively small space, must necessarily be of an extremely small diameter often not much larger than that of a human hair. Manifestly, this presents considerable difliculty in manufacture as well as in protecting the finished product from damage to the delicate winding.

Various attempts have been made to protect the winding, as for example, by covering it with a layer of heavy corded material wound over it, or by covering it with an insulating tape. It has also been suggested to encapsulate the finished product in various types of resinous materials which, aside from laborious processing steps, require baking in an oven.

The suggested methods have a number of drawbacks, foremost of which is the increased manufacturing costs due to the processing steps required to obtain a satisfactory finished prOduCt-n0t to mention the fact that a substantial number of coils are often rejected inasmuch as the protective methods may easily injure the inherently delicate construction of the coils.

Accordingly, it is a primary object of this invention to devise an electromagnetic coil construction which is simple to manufacture and eliminates the disadvantages of prior assemblies.

It is a further object of this invention to provide a coil construction in which the winding is completely protected against physical injury and the assembly is in a compact form for handling and for ultimate use.

It is a particular advantage of the invention that the finished product results in a hermetically sealed coil assembly of sturdy construction in which the winding is fully protected from damage.

It is a feature of the invention that the component elements of the protective housing and portions of the coil assembly are sealed together by a unique method utilizing sonic energy.

Other objects, features and advantages will be apparent from the following description of the invention, pointed out in particularity in the appended claims, and taken in connection with the accompanying drawings in which:

Patented Feb. 2, 1971 FIG. 1 is a front elevational view in perspective of a completed coil having terminal lugs for connection;

FIG. 2 is a similar view of a finished coil assembly utilizing terminal Wires; FIG. 3 is an exploded view, in perspective, illustrating the various elements of a coil assembly and their relative spacial relationship to each other;

FIG. 4 is a schematic representation of the application of sonic welding to the coil assembly; and

FIG. 5 is an enlarged perspective view of a coil assembly, partially in section, illustrating the interface configuration and relationship of those elements which are permanently bonded toether by the sonic welding method.

Referring to the figures, the appearance of a completed electromagnetic coil is illustrated in FIGS. 1 and 2 in which an outer housing or shell rests on the base flange 11 which is closed by a cover member 12. The sleeve 13 of the bobbin terminates in the plane of the cover 12. Terminal lugs 14 and 15 extend laterally from the coil assembly, being placed in cutouts 16 and 17 in the base flange 11. The arrangement and placement of the lugs will be further explained by reference to FIG. 3. In place of the terminal lugs 14 and 15, wire terminals 18 and 19 may be brought out through cutouts 16 and 17, respectively, as shown in FIG. 2. The function of the cover 12,

aside from closing the bottom of the coil assembly, is twofold. In one position it retains the terminals 14 and 15 and, in the other position, it assists in the separation of the wire terminals 18 and 19, as illustrated in the sectional portion of FIG. 2.

Referring to FIG. 3, the exploded views shows the base flange 11, the sleeve 13, and the retaining flange 21 which, combined in the assembled relation shown, form the bobbin over which the coil 22 is Wound.

As can be seen, the base flange 11 has an outer wall which extends coaxially with the sleeve 13 and forms a hollow portion 23 which is used to accommodate the terminal strips 14 and 15 and also the exit wires 24 and 25 of the coil 22 which are brought out through the slot 26 cut into the inner retaining wall 27 which is part of the base flange 11. The cover 12 fits over the rim 29 of the base flange 11 for sealing off the hollow portion 23. It is to be noted that the cover 12 has an inwardlyextending projection 31 of segmental shape which, as mentioned before, has a dual function. In the arrangement shown in FIG. 3, when the cover is placed over the rim 29 of the base flange 11, the projection 31 will bear down upon the lower sides of the terminal lugs 14 and 15 to hold them securely in place. On the other hand, when wire terminals are used, as seen in FIG. 2, the cover 12 is rotated in the opposite direction to that shown in FIG. 1 so that the projection 31 rests over the cutout 26 and acts as a divider against which the wires 18 and 19 are turned to extend from the coil assembly.

It should be noted that the terminal lugs 14 and 15 have lateral cutouts 33 and 33' of such width as to accept the thickness of the wall of the base flange 11. This assures a snug fitting arrangement while allowing ease of assembly.

Over the retaining flange 21 and the coil 22 fits the outer shell 10 which is of cylindrical shape so that, when the parts shown in the exploded view of FIG. 3 are properly assembled, it will result in the finished product shown in FIGS. 1 and 12.

The component elements, except for the terminal lugs 14 and 15, are of athermoplastic substance and are molded into the desired shape prior to assembly. After the coil 22 in Wound on the bobbin, the component elements are assembled ready for the final operation which is the permanent fastening of the shell 10 and the cover 12 to the base flange 11. This is accomplished in accordance with the invention in one simple operation by the use of sonic energy. Sonic Welding of thermoplastic substances is described in US. Pat. 3,224,916 to R. S. Soloif et al., issued Dec. 21, 1965, and is based on energy transfer in a material to a location where, due to a difference in density of the material, the sonic energy creates sufiicient vibratory stresses to obtain thermoplastic fusion.

In adapting sonic welding for the protective housing of the hereinabove described coil structure, a simple apparatus may be used, as shown in schematic form in FIG. 4. It consists essentially of a transducer 39 having a winding 40 which is energized from a source of sonic energy shown in block diagram. The transfer element 41, referred to in trade parlance as the horn, is so dimensioned as to fit over the coil assembly 42 placed over a platform 43 which is part of the welding apparatus. Upon intimate contact between the horn 41 and the coil assembly 42, the sonic energy is applied and fusion is effected in a matter of seconds.

The enlarged partial view in FIG. 5, in which the thicknesses of certain elements are purposely exaggerated, shows the interface joining of the coil assembly. The shell is recessed at the bottom and tapered to present a rim 45 of narrower cross section than that of the shell body. The actual contact, therefore, between the shell 10 and the base flange 11 is at this narrow rim portion. Similarly, the wall of the base flange 11 is recessed and tapered at 46 where it contacts the surface of the cover 12. The diminishing circular lines indicate, by way of explanation, the concentration of sonic energy which results in fusion. The energy is uniformly distributed around the rim of the shell 10 and the base flange 11, as well as around the rim 46 and the cover 12, resulting in a solidly-fused and hermetically-sealed structure.

The application of sonic energy is simple, fast and requires a minimum of handling in a manufacturing process. Not only is the delicate winding firmly enclosed in a housing, but the entire coil assembly becomes a solid cylindrical-shaped unit which will withstand rough handling and abuse within the physical limitations of the thermoplastic material chosen for the purpose.

The invention in its broader aspects is not limited to the specific embodiment herein shown and described but departure may be made therefrom within the scope of the accompanying claims, without departure from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. In an electromagnetic coil construction, a bobbin comprising a central sleeve having a retaining flange at one end and a base flange separated therefrom, a coil wound around said sleeve between said flanges, said base flange having a wall extending coaxially with said sleeve defining a hollow portion therebetween, a cover over said portion, said wall having cutouts accommodating terminal inserts, a shell over said coil resting on said base flange, said shell and said cover being secured to said flange by sonic welding.

2. An electromagnetic coil construction in accordance with claim 1 wherein said cover has an inwardly extending projection adapted to'engage said terminal inserts for firm retention in said base flange.

3. An electromagnetic coil construction in accordance with claim 1 wherein said cover has an inwardly extending projection adapted in one position of placement to engage said terminal inserts and in the other position to form a dividing wall for the separation of terminal leads.

4. An electromagnetic coil construction in accordance with claim 1 wherein the rim of said shell and the rim of said base flange have interface configurations for buttwelding contact with said base flange and said cover, respectively.

5. An electromagnetic coil construction in accordance with claim 1 wherein said terminal inserts comprise flat metal lugs having cutouts accepting the wall thickness of said base flange for snug fitting engagement.

6. An electromagnetic coil construction in accordance with claim 1 wherein the inner wall of said base flange engaging the winding has a slot permitting entry of the wire ends of said coil into said holow portion.

References Cited UNITED STATES PATENTS 2,787,743 4/1957 Hultgren 336l98X 2,899,655 8/1959 Forte et al. 336-498 3,230,490 1/1966 Johnson 336-198 THOMAS J. KOZMA, Primary Examiner US. Cl. X.R. 

